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  • package root
  • package args4c

    Args4c (arguments for configuration) is intended to add some helpers and utilities in obtaining a typesafe configuration from user arguments.

    Args4c (arguments for configuration) is intended to add some helpers and utilities in obtaining a typesafe configuration from user arguments.

    The core is simply to convert an Array[String] to a Config where the arguments are either paths to configuration resources or simple key=value pairs via args4c.configForArgs

    Left-most arguments take precedence. In this example, we assume 'prod.conf' is a resource on the classpath:

    MyApp foo.x=bar foo.x=ignored /opt/etc/overrides.conf prod.conf

    In addition to this core concept, this library also provides some additional configuration utilities via args4c.RichConfigOps which can be made available by extending args4c.LowPriorityArgs4cImplicits or importing args4c.implicits:

    import args4c.implicits._
    object MyApp {
       override def main(args : Array[String]) : Unit = {
         val config = args.asConfig()
         println("Starting MyApp with config:")
    
         // let's "log" our app's config on startup:
         val flatSummary : String = config.filter(_.startsWith("myapp")).summary()
         println(flatSummary) // "logging" our config
       }
    }

    Where the 'summary' will produce sorted args4c.StringEntry values with potentially sensitive entries (e.g. passwords) obscured and a source comment for some sanity as to where each entry comes from:

    myapp.foo : bar # command-line
    myapp.password : **** obscured **** # command-line
    myapp.saveTo : afile # file:/opt/etc/myapp/[email protected]3

    Also, when extracting user arguments into a configuration, an additional 'fallback' config is specified. Typically this would just be the ConfigFactory.load() configuration, but args4c uses the args4c.defaultConfig, which is essentially just the system environment variables converted from snake-caes to dotted lowercase values first, then falling back on ConfigFactory.load().

    Applications can elect to not have this behaviour and provide their own fallback configs when parsing args, but the default provides a convenience for system environment variables to override e.g. 'foo.bar.x=default' by specifying

    FOO_BAR_X=override

    as a system environment variable. Otherwise you may end up having to repeat this sort of thing all over you config:

    foo.bar=default
    foo.bar=$${?FOO_BAR}
    
    foo.bazz=default2
    foo.bazz=$${?FOO_BAZZ}
    
    ...

    Finally, args4c also provides a args4c.ConfigApp which provides some additional functionality to configuration-based applications.

p

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package root

Package Members

  1. package args4c

    Args4c (arguments for configuration) is intended to add some helpers and utilities in obtaining a typesafe configuration from user arguments.

    Args4c (arguments for configuration) is intended to add some helpers and utilities in obtaining a typesafe configuration from user arguments.

    The core is simply to convert an Array[String] to a Config where the arguments are either paths to configuration resources or simple key=value pairs via args4c.configForArgs

    Left-most arguments take precedence. In this example, we assume 'prod.conf' is a resource on the classpath:

    MyApp foo.x=bar foo.x=ignored /opt/etc/overrides.conf prod.conf

    In addition to this core concept, this library also provides some additional configuration utilities via args4c.RichConfigOps which can be made available by extending args4c.LowPriorityArgs4cImplicits or importing args4c.implicits:

    import args4c.implicits._
    object MyApp {
       override def main(args : Array[String]) : Unit = {
         val config = args.asConfig()
         println("Starting MyApp with config:")
    
         // let's "log" our app's config on startup:
         val flatSummary : String = config.filter(_.startsWith("myapp")).summary()
         println(flatSummary) // "logging" our config
       }
    }

    Where the 'summary' will produce sorted args4c.StringEntry values with potentially sensitive entries (e.g. passwords) obscured and a source comment for some sanity as to where each entry comes from:

    myapp.foo : bar # command-line
    myapp.password : **** obscured **** # command-line
    myapp.saveTo : afile # file:/opt/etc/myapp/[email protected]3

    Also, when extracting user arguments into a configuration, an additional 'fallback' config is specified. Typically this would just be the ConfigFactory.load() configuration, but args4c uses the args4c.defaultConfig, which is essentially just the system environment variables converted from snake-caes to dotted lowercase values first, then falling back on ConfigFactory.load().

    Applications can elect to not have this behaviour and provide their own fallback configs when parsing args, but the default provides a convenience for system environment variables to override e.g. 'foo.bar.x=default' by specifying

    FOO_BAR_X=override

    as a system environment variable. Otherwise you may end up having to repeat this sort of thing all over you config:

    foo.bar=default
    foo.bar=$${?FOO_BAR}
    
    foo.bazz=default2
    foo.bazz=$${?FOO_BAZZ}
    
    ...

    Finally, args4c also provides a args4c.ConfigApp which provides some additional functionality to configuration-based applications.

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